Internet

Internet is the global network of computers connected by network cables or satellite signals.

It is a network of networks so called super network.
ARPANET (Advanced Research Projects Agency Network) is the world's first operational packet switching network which is predecessor of Internet.
WWW (World Wide Web) is developed by Tim Berners Lee in 1989 while working at CERN.
WWW is a communication model used to exchange information over Internet.
URL (Uniform Resource Locator) specifies the unique address of resources over Internet.
Search engine is a website that helps users to locate their searched information over world wide web.
E.g. Google, yahoo, bing, baidu, ask.com, AOL, excite, DuckDuckGo, Wolfram Alpha, Yandex, Lycos and Chacha
A web browser is a software application to access the information on WWW.
E.g. Google Chrome, Firefox, Safari, Internet Explorer and Opera.

Protocols

Protocol is a standardized set of rules used for network communication. Below are few major protocols.

TCP/IP allows to transfer information over Internet, by breaking data into smaller pieces called packets.
IP address is unique code assigned to each computer. It is of 4 numbers separated by a dot and each number is in the range between 0 to 255. E.g. 192.168.34.12.
POP allows to receive mails.
SMTP allows to send mails.
HTTP protocol allows to access web pages as a connection between web client and web server.
FTP allows to transfer files from one computer to other.

Email is a service to exchange the messages/information among people over Internet. It is invented by Ray Tomlinson.

It has limited usage in 1960s and full usage in 1970s.
Email address is in the form of username@domainname. E.g. charan@omniguru.in
Email addresses are not case sensitive.
From - indicates sender's email address.
To - indicates recipient's email address.
CC (Carbon Copy) - indicates the recipient's email addresses who are to be informed but not a direct recipient.
BCC (Blind Carbon Copy) - indicates recipent's email addresses but hides recipient email addresses from each other.